The composition was captured by Titlow the morning after a large midsummer party in Sweden and has won the former musician a £12,000 prize
Second place was awarded to Jessica Fulford-Dobson for her portrait of a young Afghani girl with a skateboard.
A photo of nine-year-old Estonian twins by Birgit Puve came third.
Of his winning shot, Titlow said: “Everyone was a bit hazy from the previous day’s excess.
“My girlfriend passed our son to the subdued revellers on the sofa – the composition and back light was so perfect that I had to capture the moment”.
Head judge Sandy Nairne, who is director of the National Portrait Gallery, called Titlow’s portrait a “fascinating and compelling image”.
After sifting through more than 4,000 submissions from 1,793 photographers, the judges selected just 59 portraits for an exhibition at the National Portrait Gallery.
The runner-up, freelance photographer Jessica Fulford-Dobson, documented Afghan girls who attend Skateistan – an NGO born out of a small skateboarding school that met around an old, disused fountain in Kabul.
It now provides education for children, teaching leadership and cultural awareness.
“It is here that, for a few hours a week, they are able to have some semblance of a childhood in a place that is detached from the war and their working life on the streets,” said Fulford-Dobson
Third-placed Puve selected her competition entry from a book she was working on, looking at twins and triplets living in Estonia.
She visited Braian and Ryan at their great grandmother’s house in the countryside outside the capital Tallinn.
A £1,000 prize for fourth place went to Blerim Racaj for his photo Indecisive Moment, which shows a group of Kosovan teenagers sitting at the base of the National Library, a location chosen by the sitters as their ‘escape zone’.
The John Kobal New Work Award was awarded to Laura Pannack for her photograph Chayla at Shul, a portrait of a young Jewish girl.